Coded signaling apparatus



Aug. 12, 1952 c. w. FAILOR CODED SIGNALING APPARATUS Filed June 20, 19462 SHEETS SHEET 1 INVENT R lzwr'les W (ZJZOP.

III

HIS ATTORNEY C. W. FAILOR CODED SIGNALING APPARATUS Adg. 12, 1952 2SHEETS-SHEET 2 Filed June 20, 1946 INVENTOR D Em. uE. E z 9 6 08ATTORNEY Patented Aug. 12, 1952 CODED SIGNALING APPARATUS Charles W.Failcr, Forest Hills, Pa assignor to Westinghouse Air Brake Company, acorporation of Pennsylvania Application June 20, 1946, Serial No.618,026

My invention relates to coded railway signaling apparatus andparticularly to improved means for preventing improper supply of energyto a code following relay. r

In some types of coded signaling systems, as for example, a coded track:circuit signaling system, a transmitting relay is located at one end ofa pair of conductors and has contacts which are operated between twopositions in one of which they connect the winding of a code followingrelay across the conductors and in the other of which they connect asource of energy across the conductors.

The contacts of the transmitting relay are normally adjusted so that onmovement of the relay movable contacts between their two positions, thecircuits established in one position of the relay contacts areinterrupted before the circuits established in the other position of therelay contacts are established.

If the transmitter relay contacts are out of adjustment, the circuitscontrolled in both'positions of the relay contacts may be establishedsimultaneously during movement of the relay con-- tacts between theirtwo positions and energy from the source may be supplied through thetransmitter relay contacts to the winding of the code following relayand may pick up its contacts, while the supply of energy from the sourceto the wind ing of the code following relay may be interrupted when thecontacts of the transmitter relay complete their movement. If energy issupplied from the source to the winding of the code following relay overthe transmitter relay. contacts, the contacts of the code followingrelay will pick up and release and will cause energization of the codedetecting relay governed thereby even though coded energy is not beingsupplied over the cone ductors to the code following relay.

An object of this invention is to provide improved means governed by thecontacts of a transmitting relay for alternately connecting a source ofenergy and. the winding of a code fol- 6 Claims. (01. 246-48) of themovable contacts short-circuits the track battery and overlapping of thefixed contacts associated with-the other one of the movable contactsshort-circuits the code following relay,

Another object of the invention is to provide improved means of the typedescribed which employs two movable contacts of the transmitting relaywhich are connected together permanently and which control circuitsarranged so that in one position of the transmitting relay contacts acode following relay is connected across the track rails and so that inthe other position of the transmitting relay a source of energy isconnected across the track rails independently of the winding of thecode following relay. i

A further object'of the invention is to provide improved means of thetype described which employs a first transmitting relay which hascontacts movable between a first and a second position and governs asecond transmitting relay to cause its contacts to occupy correspondingpositions, and having circuits including two movable contacts of thesecond transmitting relay which are connected permanently together andmeetfective in one position to connect a code following relay across thetrack rails and effective in the other position provided a contact ofthe first transmitting relay is in the corresponding position to connecta source of energy across the track rails independently of the windingof the code following relay.

Other objects of the invention and features of novelty will be apparentfrom the following description taken in connection with the accompanyingdrawings.

I shall describe two forms of coded signaling apparatus embodying myinvention and shall then point out the novel features thereof in claims.

In practicing my invention I provide a transmitting relay together withmeans for recurrently moving the relay contacts between their twopositions. Two movable contacts of this relay are permanently connectedin series and whenrboth movable contacts are in one position establish acircuit to connect a code following relay across the rails of a tracksection, while when both movable contacts are in their other positionthey establish a circuit independent of the winding of the codefollowing relay to connect a source of energy across the track rails.These circuits are arranged so that, if one movable contactsimultaneously engages both of the associated stationary contacts, thewinding of thecode following relay will be short-circuited and so that,if the other movable contact simultaneously engages both of itsassociated stationary contacts, the source of energy is short-circuitedto thereby prevent improper supply of energy from the source to the codefollowing relay in the event that either of the contacts of thetransmitting relay is defective.

In a modification, the transmitting relay is governed by an associatedtransmitting relay which also controls the circuit for connecting thesource of energy across the track rails so that a short time interval isprovided between the instant of interruption of the supply of energyfrom the source and the instant at which the circuit for connecting thecode following relay across the track rails is completed.

In the drawings, Fig. l is a diagram of a section of railway trackequipped with coded track circuit apparatus embodying this invention,and

Fig. 2 is a diagram of a section of railway track equipped with amodified form of coded track circuit apparatus embodying my invention.

Similarly reference characters refer to similar elements in each of thetwo views.

Referring to Fig. 1 of the drawings, there is shown therein a section ofrailroad track through which traffic normally moves in the directionindicated by the arrow, that is, from left to right. The locomotiveswhich are operated in this track stretch are equipped with cab signalapparatus responsive to flow of coded alternating current energy in thetrack rails. The construction and operation or the locomotive cab signalapparatus is not a part of this invention and this equipment may bearranged as shown in Letters Patent of the United States No. 1,986,679,issued January l; .1935 to Lloyd V. Lewis for Railway TrafiicControlling Apparatus.

The track rails l and 2 of the track section shown in the drawings areseparated from the rails of the adjoining sections by insulated joints3. A code following track relay TR is connected across the section railsat the left-hand or entrance end of the section and is operated by codedenergy supplied over the section rails from the right-hand or exit endof the section. The track relay-TR controls a repeater relay TM, and italso controls an impulse relay IR which causes impulses of feed backenergy to be supplied to the rails at the entrance end of the stretch.

An approach relay AR is located at the exit end of the section and thewinding of this relay is connected across the section rails when thecontacts of the transmitter relay CTM are released.

As shown, the track section is vacant and relay AR is released so energyis supplied over front contact iii of a continuously operating codetransmitter CT and back contact 1 I of relay AR to the transmitter relayCTM and its contacts are picked up. The energy which is supplied torelay CTM is supplied from a suitable local source, such as a storagebattery, not shown, the terminals of which are designated B and C in thedrawings.

As the contacts of relay CTM are picked up, the track battery TB isconnected across the section rails over the circuit which istraced fromthe positive terminal of the battery through the secondary winding ofthe track transformer T1, and over front contacts 14 and 15 of relay CTMin series to track rail i, while the negative terminal of the battery isconnected directly to track rail 2. At this time, as the contacts ofrelay CTM are picked up, the circuit of the winding of relay AR is openat contact 15 of relay CTM so the relay AR remains released and itscontact I I maintains thecircuit of the relay CTM.

The energy supplied from battery TB to the section rails feeds over thetrack rails and over back contact I6 of relay IR to the winding of thetrack relay TR and picks up its contact to interrupt the circuits ofrelays TM and IR so that they are released.

After a short time interval contact it of code transmitter CT interruptsthe circuit of the relay CTM and its contacts release to interrupt thecircuit traced above for connecting the track battery and the secondarywinding of the track transformer across the track rails while thewinding of relay AR is connected across the track rails over the circuitwhich is traced from track rail 1 through the winding of relay AR, andback contacts 15 and I4 of relay CTM in series to track rail 2.

When the supply of energy from battery TB to the section rails is cutoil, the track relay TR releases and energy is supplied over its 'backcontact 8 to relay TM, and prior to picking up of relay TM, is suppliedto relay IR over the branch circuit which includes back contact 19 ofrelay TM. The energy supplied to relay IR prior to pickingupof relay TMpicks up the contact of relay IR, while the relay IR is snubbed by arectifier so that the relay contact remains picked up for a short timeinterval subsequent to interruption of the relay circuit. When relay IRpicks up, energy is supplied from the impulse battery IB through thewinding of track relay TR in the wrong direction to pick up the relaycontact.

The track relay 'IR and the approach relay AR are of the polar biasedneutral type, the contacts of which-pick up when and only when energyflows through the relay winding in aselected direction as indicated bythe arrow on the relay. As explained in Letters Patent of the UnitedStates No. 2,286,002, issued June 9, 1942 to Frank H. Nicholson forRailway Signaling System, this arrangement for supplying energy frombattery IB through the winding of relay TR. protects this relay againstimproper energization in the event the front and back contacts of relayIR overlap, and also protects the relay TR against operation by energyinductively discharged from the track circuit on interruption of thecircuit of the battery IB.

When relay IR picks up and connects battery IB across the section rails,energy from the battery is supplied over the section rails and over backcontacts l4 and [5 of relay CTM to the winding of relay AR and picks upthe contacts of the. relay AR. On release of relay IR, the supply ofenergy from the battery IE to the relay AR is cut off and relay ARreleases and closes its back contact I l in the circuit of relay CTM sothat energy is supplied to relay CTM during the next closed period ofcontact H] of the code transmitter CT.

The contact ill of the code transmitter CT continuously operates betweenits two positions at a predetermined rate, such as 75 or times a minuteso it is closed shortly alter release of relay AR. Accordingly, energyis supplied to re lay CTM and its contacts pick up to interrupt thecircuit of relay AR and connect the track battery and the secondarywinding of the track transformer TT across the section rails with theresult that energy from the battery feeds to the track relay TR andpicks up its contact i8. When the track relay TR icks up, the supply ofenergy to relay TM is interrupted and its contacts release. A resistanceis connected acrossthe terminals of the winding of relay TM and, .oninterruption of the 'supply'of energy to the relay winding, delaysrelease of. the relay contacts slightly to compensate for the delay inpicking up. of the relay contacts on the supply of energy to the. relaywinding and thereby substantially;'equalizes the picked-up andreleasedperiods ofithe contacts of the relay 'IM.:,

After a short interval, contact I of the code transmitter CTinterruptsthe circuit. of the relay CTM and its contacts release to cutoff the'supply of energy from battery TB torelay TR and the contact ofrelay TR releases to establish the circuits of relays TM and IR so thatthe contact of relayIR picks up to cause an impulse of energy to besupplied from battery IE to the relay AR.

As long as the section is vacant, the equipment continues to operateasdescribed and as'a result of movement of the contacts of relay TM energyis supplied through the decoding transformer DT to the relay H and itscontacts are picked up. The relay H may be employed-for any suitablepurpose, such as to control a signal, not shown, for governing movementof traflic in the stretch. Likewise, movement of the contacts of therelay AR causes energy to be supplied through the decoding transformerADT to relay AH and its contacts arepicked up with the result that itscontact 20 short-circuits the primary winding of the track transformerTI. The relay AH is provided with other contacts which control circuitswhich may be employed for any appropriate purpose. 7

When a train enters the section, the track rails are shunted and energysupplied from battery TB ceases to operate relay TR and it remainsreleased sorelay TM is steadily picked up while relay IR remainsreleased and does not supply energy from battery IE to the sectionrails. Accordingly, relay AR remains released andits contact IImaintains the circuit of relay CTM and relay CTM continues to beoperated by the.

code transmitter CT.

is no longer supplied through the decoding transformer DT to relay H andits contacts release. Similarly, when relay AR remains released, energyis not supplied through transformer ADT to relay AH and its contactsrelease so that contact 20 establishes the circuit for supplyingalternating current energy to the primary winding of track transformerTT froma source the terminals of which are designated BX and CK.Accordingly, during the pick-up periods of the relay CTM, alternatingcurrent energy is supplied from the secondary winding of the tracktransformer T1 to the section, rails and operates the locomotive cabsignal equipment.

When the section is vacated, energy supplied from battery TB to thesection rails again operates the track relay TR while relay IR againoperates to supply energy from battery IE to the relay AR. As a resultof operationfof relay TR the relay H picks up, and as a result ofoperation of relay AR the relay AH picks up to interrupt the supply ofenergy to the primary winding of transformer TT and to short-circuitthis winding.

This equipment is arranged so that if the contacts of relay CTM are outof I adjustment,

with the result that either of the movable contacts I4 and I5 engagesits front and its back points of contact simultaneously, energy will'notbe supplied from'battery TB or from the track transformer TT to therelay AR.

6 tTsIf contact I4engages its front and backpoint's of contactsimultaneously,'the track battery and the secondary windingof thetransformer TT are short-circuited over the circuit which is traced fromthe positive terminal of the battery through the transformer, secondarywinding, and" thence to the negative terminal of the battery throughfront and, back points of contact of contact. I4, which are assumed tooverlap orengage. the battery and transformer are short-circuited,- en,-ergy will not be supplied to relay AR regardless of the position ofcontact I5, and there is. no danger that the contacts of relay AR willbe picked up and released because of the supply of energy to the relaywinding from the battery'I'B or the transformer I g If contact I5engages its front and back points of contact simultaneously, the windingof relay AR is short-circuited through the contact I5, as isobvious-from the drawing, and the relay AR will not be operated byenergy supplied from battery TB or the transformer TT. I v

If the contacts I4 and I5 are out ofadjustment so that front contact I4and back contact I5 engage simultaneously, energy may be supplied fromthe battery TB and the transformer TT through the winding of relay AR tothe track rails. However, the energy supplied from the battery flowsthrough the winding of relay AR in the wrong direction to pick up therelay contacts. The alternating current energy supplied from transformerTT to the winding of relay AR is of relatively high frequency, and thecontacts of relay AR may not operate rapidly enough to respond to' thisenergy, but if they do, the rate of operation of the contacts is so highthat too.

little energy is supplied through the decoding transformer ADT to relayAH to pick up the relay contacts or to maintain them packed up.

Accordingly, relay AH is released under thesev conditions.

.If the contacts I4 and I5 are out of adjustment so that back contact I4and front contact I 5 engage simultaneously, the back rails I and 2 areshort-circuited and the relay AR isv certainv to' remain released. Thecircuit of the relay AR is arranged so that energy inductivelydischarged from the track circuit on interruption of the circuit of thetrack battery will not, pick up the contacts of the relay AR. When thecontacts of relay CTM are picked up, the battery TB is connected acrossthe track rails with the positive terminal of the battery connected totrack rail I so that energy flows from the battery to track rail I,thence to trackv rail 2 and the negative terminal of the battery throughthe winding of track relay TR, on through the wheels and axles of avehicle. if the section is occupied. Because of the inductance of thetrack circuit, an impulse of energy is in duced in the trackcircuit whenthe supply of energy from the battery to the track rails is interruptedby opening of front contacts I4 and.

I 5 of relay CTM, and, on closing of back contacts I4 and I5 of relayCTM, this energy is supplied to the. winding of relay AR. The energysupplied at this time flows in the same direction as that supplied fromthe battery, and therefore flows from track rail I to track rail 2, overback contacts I4 and I5 of relay CTM and through the winding of relay ARfrom right to leftto track rail I. This impulse of energy, therefore,flows through the winding of relay AR in the wrong direction to pick upthe relay contacts. so. there is .no possibility that the relay contactswill be improperly picked :up by the energy inductively discharged fromthe track circuit.

. As a result of the supply of energy from the track battery TB to thetrack rails, a charge may .be built up in the track ballast so that theballast and the track rails together in effect form a storage batteryfrom which energy may be supplied to the winding of the relay AR whenthe relay winding is'c'onne'cted across the track rails. However, thevoltage of the energy supplied from this source to the relay AR isrelatively low and although this energy flows through the winding ofrelay AR in the proper direction to pick up the contacts of relay AR,insufficient energy flows through the winding of relay AR to pick up therelay contacts, and the relay contactswill not be picked "up improperlyby energy supplied from this source.

It willbe seen, therefore, that the track battery and track transformerand the relay AR are alternately connected across the section rails bycontacts of the transmitter relay CTM, but that the connections governedby the contacts of the relay CTM are arranged so that, in the event thecontacts of relay CTM are out of adjustment, there is no possibilitythat the relay AR will be operated by energy from the battery TB or thetransformer TT so as to improperly energize the relay AR. Similarly, thevarious parts of the track circuit are arranged so that the contacts ofrelay AR will not be improperly picked up by energy'inductivelydischarged from the track circuit or by energy stored in the trackcircuit. Accordingly, the relay AH is certain to remain released unlessthe relay AR is being operated by coded energy supplied over the sectionrails and the relay AH, therefore, reliably indicates whether thesection is occupied or not.

The arrangement provided by thisinvention is also adapted for use intrack sections where feed-back energy of both polarities is employed andFig. 2 is a diagram showing this modification. The apparatus of Fig. 2is generally similar to that shown in Fig. 1 but differs therefrom inthat two code following approach relays are provided at the exit end ofthe section. These relays are designated ARN and ARR and are of thebiased polar type, like relay TR, but are arranged so that they respondto feed-back energy of opposite polarities. In addition, a repeaterrelay CTMM is provided for the transmitter relay CTM to provide an opencircuit interval following interruption .of the circuit of the trackbattery TB and thus prevent operation of either of the approach relaysbyenergy inductively discharged from the track circuit.

At the entrance end of the section, a pole changing relay PC governs thepolarity of the energy supplied from the battery IE to the track rails,while a repeater relay IM is provided for the. impulse relay IR toprovide an open circuit interval following interruption of the. circuitof the batteryIB and thus prevent operation of the track relay by energyinductively discharged from the track circuit. The relay PC may becontrolled in any suitable manner, not shown, as, for example, by traihcconditions in the section tothe left of the section shown.

The apparatus of Fig. 2 is shown in the condition which it assumes whenthe track stretch is vacant and an impulse of energy is'being suppliedfrom' the track battery to the track relay. At this time contact of thecode transmitter CT is closed and supplies energy to the transmitterrelay CTM and "its contacts are picked up with the result that energy issupplied over its front contact :25, back contact 26. of relay ARR, andback contact2] of relay ARN to relay CTMM and its contacts :are pickedup. As relays CTM and CTMM are picked up, the track battery TB and tracktransformer TT are connected across the track rails over the circuitwhich is traced from the positive terminal of the battery through thesecondary winding of transformer 'IT, over front contact 38 of relayCTM, and front contacts 3| and 32 of relay CTMM in series to track railI, while the negative terminal of the battery is connected directly totrack rail 2.

The energy supplied from battery TB to the track rails is supplied tothe winding of track relay TR over the circuit which is traced fromtrack rail 1 through the track relay winding from left to right, backcontact 35 of relay IR, and back contacts 36 and 31 of relay IM inseries to track rail 2. The energy supplied to the track relay TR picksup its contact I8 to interrupt the circuit of relay TM and of relays IRand IM and these relays are released.

After a short time interval th contact 19 of code transmitter CT opensand opens the circuit of relay CTM and its contacts release so thatcontact 25 interrupts the circuit of relay CTMM while contact 38interrupts the circuit of the battery TB and of the track transformerTT. The relay CTM is snubbed by a rectifier and resist: ance so releaseof the relay contacts is delayed slightly after interruption of thecircuit of the relay winding to compensate for the pick-up time of therelay and thus equalize the pickedup and released times of the relaycontacts. The relay CTMM is also snubbed by a rectifierand a resistor sothe contacts of this relay do not release for a short period after thesupply of energy to the'relay winding is interrupted by release ofcontact 25 of relay CTM.

In the period between release of relays CTM and CTMM the track rails areshort-circuited over the circuit which is traced from track rail I overfront contacts 32 and 3! of relay CTMM in series and back contact 30 ofrelay CTM to track rail 2. This short-circuiting of the track railsdischarges energy stored in the track ballast and also dissipates theenergy impulse induced in the track circuit on interruption of thecircuit of the track battery and prevents this energy impulse from beingsupplied to the relays ARN and ARR. Where only one approach relay isemployed, as in Fig. 1, the equipment can be arranged so that theimpulse of energy inductively discharged from the track circuit is ofthe wrong polarity to operate the approach relay, but where two approachrelays, which are responsive to energy of opposite polarities areemployed, this method of protecting the approach relays cannot beemployed and the time interval provided by the relay CTMM is providedfor this purpose.

When the supply of energy from battery TB is cut off, the track relay TRreleases and energy is supplied over its back contact 18 to relay TM,and is also supplied over back contact 19 of relay TM to relay IR, and,in addition, over back contact 39 of relay IR to relay IM. The supply ofenergy to relays IR and IM is cut off as soon-as relay TM picks up butthe apparatus is arranged so the relays IR and IM will be picked up bythe energy supplied thereto prior to picking up of relay I'M. Afterrelay IR picks up, energy is supplied to relay IM over the front contact39 of relay IR so the relay IM will remain picked up as long as relay IRis picked up. The relay When relays IR and IM are both picked up,

the battery IB is connected across the track rails so as to supplyenergy of normal or reverse polarity according as the contacts of relayPC are picked up or released. As shown, the contacts of relay PC arepicked up and when relays IR and IM are both picked up, the positiveterminal of battery IB is connected over front contact 40 of relay PC,front contact 4| of relay IR and front contacts 3'! and 3-6 of relay IMin series to track rail I, while the negative terminal of the batteryisconnected over/front contact 42 of relay PC to track'rail 2. The energysupplied from battery IE to the track rails is supplied to relays ARNand ARR in series over the circuit which is traced from track rail Ithrough the winding of' relay ARN from left to right, over back contacts32 and 3| of relay CTMM in series, and through the winding of relay ARRfrom left to right to track rail 2. l

The energy supplied from battery 13 when relay PC is picked up is of thepolarity eifective to pick up the contacts of relay ARN but not relay.

ARR. When relay ARN picks up, its contact 21 interrupts the circuit ofrelay CTMM to insure that relay CTMM remains released and maintains thecircuit of the relays ARN and ARR. As relay CTMM cannot pick up whenrelay ARN or relay ARR is picked up there is no possibility that relayARN or ARR, when picked up, will be released as a result of picking upof relay CTMM. Accordingly, if foreign current is present and picks upone of the relaysARN or ARR, the relay will be steadily picked up andwill not cause energy to be supplied through the associated decodingtransformer, as would occur if the relay were recurrently releasedbecause of picking up of relay CTMM. The relays ARN and ARR, therefore,will not operate as code following relays if foreign current is presentand the relays AHN and AHR will both be released.

When relay ARN or ARR is picked up, the circuit of the relay CTM is notaffected and it continues to be operated by the code transmitter CT.However, picking up of relay CTM does not affect the circuit of therelays ARN and ARR, and picking up of relay CTM with relay CTMM releaseddoes not result in the supply of energy from the track battery TB or thetrack transformer to the section rails.

Returning to the equipment at the entrance end of the section, the relayIR releases after a short interval and its contact 4| interrupts thecircuit of battery IB and its contact 39 interrupts the circuit of relayIM, but the snub for relay IM delays release of its contacts for a shortinterval. After release of relay IR, but before release of relay IM, thetrack rails are shortcircuited over the circuit which is traced fromtrack rail l over front contacts 36 and 31 of relay IM in series andback contact 4| of relay IR to track rail 2. The short-circuiting of thetrack rails discharges energy stored in the track ballast and itdissipates the impulse of energy inductively discharged from the trackcircuit on interruption of the supply of the circuit of battery IB andthus prevents picking up of the contact of relay 10 TR by this energy.Where the energy supplied from battery IB tothe section rails is alwaysof the same polarity, the arrangement shown in Fig. 1 may be employed toprevent picking up of the track relay by energy inductively dischargedfrom the track circuit, but where the energy supplied frombattery IB isat times of one polarity and at other times of the other polarity, thearrangement shown in Fig. 2 mustbe employed.

The relay IM releases shortly after reIayIIR and interrupts the circuittraced above for shortcircuiting the track rails and establishes thepreviously traced circuit for connecting the track relay TR across thetrack rails.:

- When the supply of energy from battery 13 is cut off, the relay ARNreleases and its back contact 21 is closed to permit energy to besupplied to relay CTMM. 1

On subsequent closing of contact I0 of the code transmitter CT,,.energyis supplied to relay CTM, and prior to picking up of relay CTM, is alsosupplied torelay CTMM over back contact 25 of relay CTM so that relayCTMM will pick up concurrently with relay CTM. When relay CTM picks up,its contact 25 establishes a circuit for energizing relay CTMM to keepit picked up as long as relay CTM is picked up. When relays CTM and CTMMare picked up, energyis again supplied from the battery TB over thesection rails to relay TR and its contact I8 is picked up to releaserelay TM, while the equipment thereafter operates as previouslydescribed,

As a result of operation of relay TM energy is supplied through thedecoding transformerDT to the relay H and its contacts are picked up.Similarly, as a result of operation of relay ARN energy is suppliedthrough the transformer NDT to relay AHN and its contacts are picked up.with the result that, the primary winding of transformer TT is,short-circuited over the circuit which includes back contact 45 of relayAI-IR and front contact of relay AHN.

On the approach of a train. the contacts of relay PC may be released bymeans not shown, thereby changing the polarity of the energy suppliedfrom battery IB. After release of relay PC the positive terminal ofbattery '13 is connected over back contact 42 of relay PC to track rail2, While during the picked-up periods of r'elaysIR and 1M the negativeterminal of the battery is connected over back contact All of relay PC,front contact 4| of relay IR, and front contacts Hand 36 of relay IMinseries to track rail I. The energy supplied -from battery IB at thistime flows from rail 2 through the winding of relayARR from right toleft, over back contacts 3| and 32 of relay CTMM in series, and throughthe winding of relay ARN from right to left to track rail I. Thisenergy, therefore, is effective to operate relay ARR but not relay ARN,and as a result the relay AHR is picked up while relay AHN releases.After relay AI-IR picks up, the primary winding of transformer TT isshort-circuited over front contact 45 of relay AHR, while they operationof the equipment is otherwise unchanged.

When the train enters the track section shown, the track relay TR isshunted and remains released and establishes the circuit of the relay TMso that its contacts are steadily picked up and energy is no longersupplied to relay H and it releases while contact IQ of relay TMinterrupts the circuits of the relays IR and IM and they remain releasedso that energy is no longer supplied from battery IE to the sectionrails and relaysARN and ARR both remain released. Accordingly, relayAHR, releases and relay AI-IN remains released and energy is. suppliedover back contact 46 of relay AHN and back contact 4-5. of relay AHR tothe. primary winding of track transformer 'IT. so. that duringsubsequent picked-up periods of the relays CTM and CTMM alternatingcurrent energy, is. supplied from the transformer secondary winding to.the track rails to operatethe cab signal apparatus on the locomotive inthe track section.

When the section is vacated, energy frombattery TB again feeds to trackrelay TR and picks up its contact [8 and relay TM release so that onsubsequent release of relay 'IBenergy is supplied over back contact ifof relay TM to relays IR and IM'and they pick up to. supply energy frombattery IE to the section rails. This energy picks up one or theother-oi the relays ARN or ARR, depending on the polarity of the energy,with the result that one of the relays AHN or AHR. picks up to. cut offthe supply of energy to transformer TT and to short-circuit thetransformer primary winding. Similarly, as a result ofoperation of thetrack relay TR, the relay I-I picks up and the equipment is againsubstantially in the condition in which it is shown in the drawings.

This equipment is arranged so that defects in the contacts. of relaysCTM, and CTMM, or abnormal operation of these contacts, cannot result inobjectionable supply of energy from the battery TB. or the transformerIT to the relays ARN and ARR, or in picking up of either of the relaysARN or ARR by the energy inductively discharged from the track circuiton interruption of the circuit of the track battery.

If the front and backpoints of contact or" movable contact 38 of relayCTM engage simultaneously, the track battery TB and the primary windingof the track transformer T1 are shortcircuited and. energy will not be,supplied to. the relays ARN and ARR even if'the contacts of relay CTMMare released.

If front contact 30 of relay CTM is closed and contacts 31 and 3-2 ofrelay CTMM are released, energy cannot be supplied from the battery TBand the transformer TT to the relays ARN and ARR since the circuit ofthe battery and transformer is open at front contact 3| of relay CTMM.

If movable contact 3| of relay CTMM engages its front and back contactssimultaneously, a

circuit will be established from battery TB and,

transformer TT through the winding of relay ARR. during the picked-upperiods of contact 38 of relay CTNL, At such times energy may besupplied from the positive terminal of the battery TB through thesecondary winding of trans.- former TT, over front. contact 38 of relayCTM, through. front and back points. of contact of con.- tact 3i orrelay CTMM, which. are assumed to engage simultaneously, and throughthe. winding of relay ARR from leftto right to the negative terminal ofthe battery. The energy supplied. from the battery to the winding of.relay ARR. flows through the relay winding in the wrong direction topick up the relay contacts so they remain released and. this supply ofenergy to relay ARR cannot produce an objectionable result. If energy issupplied from transformer IT to relay ARR, over the circuit tracedabove, the. relay contacts, if they operate. at all, will operate sorapidly that insufiiciently energy will be supplied through thetransformer EDT to r'elay AHR to pick up its contacts.

Under the conditions stated namely, when the front and back contacts ofcontact 3;! engage simultaneously, if back contact 32 is closed, energymay be supplied from battery: TBv and transformer T1 through the windingof relay ARN to the track circuit. This will also be true if thecontacts of relay CTMM' are out or adjustment so that front, contact 3iand back contact 32 engage simultaneously. At. such times the positiveterminal of the battery TB is connected through the secondary winding oftrans-V former TT, over front contact 33 of relay CTM, front ccntact 3;!back contact 3-2 of relay CTMM, and through the windingof relay ARN fromright to left to track rail l, while the negative terminal of thebattery is connected to track rail 2. The energy supplied from thebattery through the winding of relay ARN flowsthrough the relay windingin the wrong direction to pick up the relay contacts and there is nodanger that relay ARN will be operated improperly. As explained above,energyirom thetransformer TT may be supplied through the winding otrelayARN but cannot cause energizationof relay Ali-1N.

If the front and back points of contact of movable contact 312 engagesimultaneously, the

winding of relay ARN will be short-circuited and energy will not besupplied through this winding regardless of the position of contact atof relay C'IMM or contact tllcf relay CTM. Ac cordingly, the contacts ofrelay ARN remain released and will not cause improper energizetion ofrelay AHN. r

If front contact 32 and back contact iii of relay CTMM engagesimultaneously, the relay ARR, will be connected across the track rails,

but the circuit of the battery TB and; of the transformer TT is open atfront contact 3;! of relay CTMM and energy will not be supplied from thebattery or the transformer to, either the relay ARR or the track circuitand relay ARR remains released, while, the circuit of the winding ofrelay ARN is open at, back contact 32 of relay CTMM and relay- AR-Nremains released.

The equipment at the exit; end of the section is also arranged; so thatthe;- impulse of energy induced in the track circuit on interruption ofthe, circuit of the-battery 'IBwill not; be supplied to relay ARN orARR. and will notoperate their contacts. Energy is supplied from battery'13)?-v to the track rails only when relays- CTM and- CTMlVl are bothpicked up, and when relay EZ'IIM is picked up its contact 2%establishes: a circuit for relay C'Im so that the contactsof relay CTMMremain picked up as lon as relay CFIM is picked; up. On interruptioncfthe circuit of the relay CTM by contact 1a of the code transmitter CTthe contacts of relay- CTM release with the, result, thatcontact;Siliinterrupts the circuit or" battery TB and contact. 2-5. interruptsthe circuit of the relay CTMM; but, becauseof; the rectifier andresistance snub, connected across the terminals of the winding'of relayCTMM', the

CTM, e: now. f ene y: the. r ck: c r uit ceases and an impulse of energyis induced the track circuit. When contact 3;") of relay CTM engagesits. back contact, the contacts of relay relay TR. If movable contact 4|of relay IR,

engages its front and its back points of contact simultaneously, thebattery IB will be shortcircuited and energy will not. be supplied fromthe battery to either thetrack relay or the track circuitand the contactofthe track relay will remain; released and maintain the circuit of therelay TM so that relay I-I remains released. H

v If front contact 4| and backcontact 35, of relay IR are closedsimultaneously, energy will not be supplied from battery IE to relay TRas,

the circuit of relay IR is open at back contact 36 of relay IM, if thecontacts of relay IM are picked up, or at front contact 31, if thecontacts of relay IM are released. v r v If movable contact 31 of relayIM engages its front and back points of contact simultaneously, thebattery IE will be short-circuited when contact 4! of relay IR is pickedup and energy will not be supplied from the battery 13 to the relay TRregardlessof the position of contact 36 of relay IM or contact 35 ofrelay IR.

Similarly, if movable contact 36 of relay IM engages its front and backpoints of contact simultaneously, the winding of relay TR will be'short-circuited if back contact 35- of relay IR is closed to establishthe circuit of this winding. As the winding of the track relay isshort-circuited the relay contact is certain to remainreleased.

As was explained in detail above the relays IR and IM cooperate toprevent energization of relay TR by the impulse of energy inductivelydischarged from the track circuit on interruption of the circuit of thebattery 113.

Although I have herein shown and described only two forms of apparatusembodying my invention, it is understood vthat variouschanges,

,50 the scope of the appended claims without departing from the spiritand scope of my invenand modifications may be made therein within tion.

Having thus described my invention, what I claim is:

1. In combination, a first and a second conductor extending between twospaced locations, and apparatus at one of said locations, at least, foralternately supplying coded energy to said conductors and for receivingcoded energy from said conductors comprising a transmitter relay havinga'first and a second movable contact which are connected directlytogether and are moved periodically between a first and a secondposition substantially in synchronism, a code following relay having oneterminal of its winding connected permanently to said first conductorand having a contact biased to a first position and movable to a secondposition when and only when energy is received from said conductorswhich flows through the relay winding in the positive to negativedirection from said first conductor to said second conductor, a sourceof direct current energy having its negative terminal permanentlyconnected to said second conductor, said transmitter relay first movablecontact being effective according as it is inv itsfirst' or its secondposition to connect said transmitter relay second movable contact tosaid second con-' ductor or to the positive :terminalyof said source ofdirect current, said, transmitter relaysecondmovable contact beingeffective. accordingas-it is in its first or its second position tconnectsaid transmitter relay first movable contact to the otherterminal of the winding of said code following relay or to said firstconductonand a detector relay responsive to the periodic movefollowingrelay ment of the contact of said code between its'two positions.

, 2. In a coded signaling system,

a first and a second location, a first code following relay at saidfirst location responsive to direct current impulses received over saidconductors, a first source, of direct current at said first location forsupplying impulses to said conductors during the intervals between thereceived impulses, said first source having its positive terminalconnected to the first conductor, a second code following relay havingone terminal connected perma-- nently to said first conductor and asecond source ofv direct current having one terminal connectedpermanently to said second conductor, both atsaid second location, atransmitter relay at said second location having a first and a second-mov-' able contact which are electrically connected to-- gether.permanently and are moved periodically between a first and a secondposition substantially in synchronism, a circuit including both of saidtransmitter relay contacts in series for connecting the winding ofsaidsecond code fol- I lowing relay across said conductors when both of saidtransmitter relay contacts are in the'irfirst position, a circuitincluding both of said transmitter relay contacts in seriesforconnecting'said second source of direct current across saidconductors with the positive terminal of said sec-'- ond sourceconnected to said first conductorwhen both of said transmitter relaycontacts arein their second position, said second code following relayhaving a contact biased to a first position and movable therefrom to asecond position when and only when current flows in the positivetonegative direction through the relay winding from the terminal which isconnected to said first conductor to the terminal which is connected tosaid second conductor, and a code detecting relayresponsive to codefollowing operation of said second code following relay.

supplying coded energy to said track rails and for receiving codedenergy from said track rails,

comprising a first transmitter relay having contacts which are movedbetween a first and a sec?" ond position, a second transmitter relayhavin'g' a first and a second movable contact whichare; electricallyconnected together and are movable' in combination, a first and a'secondconductor extending between 3. In a coded track circuit signalingsystem, in combination, a section of railway track having a pair oftrack rails, and apparatus for alternately nately supplying coded energyof. a given relative.

polarity to said track railsandcforreceiving coded energy of either oftwo polarities from the track rails, comprising a first transmitterrelay having contactswhich are moved. between a first and a secondposition, a second transmitterrelay having 7 a first and a secondmovable contact which. are electrically connected together and aremovable periodically between afirst and a second position. substantiallyinsynchronism, circuit means governed by said first transmitter relayfor operatingthe, second transmitter relay to-cause its contacts tooccupy their. first or their second. position according as the contactsof the first transmitter relay occupy their first or theirsecondposition, said first movable contact being effective accordingas'it is in its first or its second position to connect saidsecondmovable contact to'one of said track rails directly or through thewinding of a first code followingv relay which is-responsive to energyof one polarity only, said. second movable contact beingcefiectiveaccording as it is in its second or its first position to connectv saidfirst movable, contact, to the other of said track rails through thewinding of a second code following relay or through asourcc of. energyprovided a contact of saidfirst transmitter relay is in itsfirstposition, said. code following relays eachhaving contacts biased to areleased position and movable therefrom to a picked-up position. whenand only when energy fiowscthrough the relay winding in a selecteddirection, the circuits for connecting said code following relays andsaid. source across the track rails being arranged; so

thatthese relays respond to opposite polarities of energy suppliedoverthe track circuits and so that theenergy supplied from said sourceto'the track rails is of the same polarity as that which is efiective topick up the'contacts of said second codefollowing; relay. 1

5; In a coded track'circuit signaling system, J

in combination, a section-of'railway track having a pair of track rails,and apparatus for alternately supplying-coded energy to said track railsandfor receiving-coded energy from saidtrack rails, comprising afirsttransmitter relay having contacts which are moved between a first and asecond.

position, a second transmitter relay having a first and a second movablecontact which are electrically connected-together and are movableperiodically between a'first and a second position substantially insynchronism, circuit meansgovrelay occupy their firstlor their secondposition,

said first movable. contact being effectiveaccord ing as it is in itsfirst or its second position to connect said second movable contact toone of said track rails directly or through the winding of a codefollowing. relay, said second movable contact being efiective when inits first position to connect said first movable contact to the other ofsaid. track rails through a source of energy provided a contact'of saidfirst transmitter relay is in its first'position and-being effectivewhen in its second position to establish a connection between said firstmovable contact and said other track rail irrespective of the positionof the con-- tacts of said first transmitter relay.

6. In a coded track circuitsignaling system. in combination, a sectionof railway track having apair oftrack rails; andapparatus foralternately supplying coded energy to said conductors and for receivingcoded energy from said con- 25:

ductors, comprising a first transmitter relay having contacts which aremoved between a first and a second position; a second transmitter relayhaving a; first and-a second movable contact which are electricallyconnected together and are movable periodically between a first and asecond posi-- tion substantially in synchronism, circuit means governedby said first transmitter relay for oper-' ating the second transmitterrelay to cause its contacts to occupy their first or their secondposition according as the contacts of the first transmitter relay occupytheir first or their second position, acode following relay having thefirst terminal of its winding connected to one of said track rails, saidfirst movable contact being efiective according as it is in its firstorits sec ond position to connect said second movablejcontact to saidone track rail or'to the second terminal oi the Winding of said" codefollowing relay, saidsecond movable contact being efiective when in itsfirst positionto connect said first movable contact to the other of saidtrack rails through a source of energy provided a contact of said firsttransmitter relay isiin its first position, saidsecond rnovable contactbeing effective when in itssecond position to establish a connectionfrom said. first movable contact to-said other track rail irrespectiveof the position-of thecon tacts of said first transmitter relay. 1

CHARLES W.FAILOR;

err cannons orrnn Thedollowing-refrences are of record'in the file otthis patent:

UNITED STATES PATENTS

